Starch bioavailability in the upper gastrointestinal tract of colectomized rats.

Colectomized rats were used to compare the bioavailability of starch from canned peas, kidney beans, lima beans, corn, cooked rice and AIN-76A purified diet. Postoperative weight gains of colectomized and sham-operated rats were not different. Test meals of approximately 2 and approximately 3.3 g (dry weight) of each food containing chromic oxide (0.6 g/100 g) were administered to 4-6 rats by gastric intubation. Chromium recovery in ileal digesta 10 h after the meal ranged from 94 to 102%. Significant starch (11-15%) from peas, lima beans or kidney beans was recovered in the ileal digesta; 0.2-0.4% of starch from rice, corn or AIN-76A was in the ileal digesta. Pretreatment of kidney or lima beans with a heat-stable endo-alpha-amylase decreased the starch recovered in the ileal digesta to 2.7-4.3% of that fed; pretreatment with the amylase and pepsin had no further effect. Oligosaccharide extraction, the size of the test meal and the amount of starch did not affect starch bioavailability.